Don't hardcode 0 and 255 anymore. Instead use pwm_min and pwm_max as
boundaries when converting from a speed (0 to 100) to a pwm value.
0 gets mapped to pwm_min, 100 gets mapped to pwm_max everything inbetween
gets linearly interpoltated.
1. The fanspeeds can now be specified as floats for better granularity
2. Removed 4 as the lowest possible speed. Lowest possible value is now 0.0
3. min and max values are now correctly read for pwm1 and not the rpm
values of fan1 anymore
4. Percentage speed now gets correctly converted to the pwm values
(usually between 0 and 255)
5. Before the update of the pwm-value was skipped when the current speed
was below minimum or above maximum. This got removed. Why was that
there in the first place?
6. Simpler algorithm for speed_for_temp
7. in monitor the min value is now actually below MIN and the max value
below MAX. Before it was swapped
8. Fixed grammar error "can's" instead of "can't"
